memblock: introduce saner 'memblock_free_ptr()' interface

The boot-time allocation interface for memblock is a mess, with
'memblock_alloc()' returning a virtual pointer, but then you are
supposed to free it with 'memblock_free()' that takes a _physical_
address.

Not only is that all kinds of strange and illogical, but it actually
causes bugs, when people then use it like a normal allocation function,
and it fails spectacularly on a NULL pointer:

   https://lore.kernel.org/all/20210912140820.GD25450@xsang-OptiPlex-9020/

or just random memory corruption if the debug checks don't catch it:

   https://lore.kernel.org/all/61ab2d0c-3313-aaab-514c-e15b7aa054a0@suse.cz/

I really don't want to apply patches that treat the symptoms, when the
fundamental cause is this horribly confusing interface.

I started out looking at just automating a sane replacement sequence,
but because of this mix or virtual and physical addresses, and because
people have used the "__pa()" macro that can take either a regular
kernel pointer, or just the raw "unsigned long" address, it's all quite
messy.

So this just introduces a new saner interface for freeing a virtual
address that was allocated using 'memblock_alloc()', and that was kept
as a regular kernel pointer.  And then it converts a couple of users
that are obvious and easy to test, including the 'xbc_nodes' case in
lib/bootconfig.c that caused problems.

Reported-by: kernel test robot <oliver.sang@intel.com>
Fixes: 40caa127f3c7 ("init: bootconfig: Remove all bootconfig data when the init memory is removed")
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 5 insertions, 8 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 78a32b956e81..5afd98559193 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -135,7 +135,7 @@ static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align)
 
 static void __init pcpu_fc_free(void *ptr, size_t size)
 {
-	memblock_free(__pa(ptr), size);
+	memblock_free_ptr(ptr, size);
 }
 
 static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 1a50434c8a4d..ef885370719a 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -49,8 +49,7 @@ static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
 			p = early_alloc(PMD_SIZE, nid, false);
 			if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
 				return;
-			else if (p)
-				memblock_free(__pa(p), PMD_SIZE);
+			memblock_free_ptr(p, PMD_SIZE);
 		}
 
 		p = early_alloc(PAGE_SIZE, nid, true);
@@ -86,8 +85,7 @@ static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
 			p = early_alloc(PUD_SIZE, nid, false);
 			if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
 				return;
-			else if (p)
-				memblock_free(__pa(p), PUD_SIZE);
+			memblock_free_ptr(p, PUD_SIZE);
 		}
 
 		p = early_alloc(PAGE_SIZE, nid, true);
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index a1b5c71099e6..1e9b93b088db 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -355,7 +355,7 @@ void __init numa_reset_distance(void)
 
 	/* numa_distance could be 1LU marking allocation failure, test cnt */
 	if (numa_distance_cnt)
-		memblock_free(__pa(numa_distance), size);
+		memblock_free_ptr(numa_distance, size);
 	numa_distance_cnt = 0;
 	numa_distance = NULL;	/* enable table creation */
 }
diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index 737491b13728..e801e30089c4 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -517,8 +517,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 	}
 
 	/* free the copied physical distance table */
-	if (phys_dist)
-		memblock_free(__pa(phys_dist), phys_size);
+	memblock_free_ptr(phys_dist, phys_size);
 	return;
 
 no_emu: